1. Field of the Invention
The present invention is concerned with a timepiece used while being carried like a wristwatch, a pocket watch or the like, and relates especially to a timepiece possessing a rotatable bezel.
2. Description of the Related Art
Hitherto, the bezel rotatably disposed in a case band is made so as to be retained in a desired operative position by a constitution giving a click feeling following upon its rotation operation. As a constitution for it, there are known a click ball type and a leaf spring type.
The click ball type possesses a constitution in which, in a back face of the bezel, there is provided a click groove formed with engagement teeth comprising plural irregularities juxtaposed in a rotation direction of this bezel and, in the case band, there are provided a steel ball engaged with and disengaged from the engagement teeth, and a coil spring pushing this steel ball to the engagement teeth. In this constitution, if the bezel is arbitrarily rotated in any direction of a clockwise direction and a counterclockwise direction, since the coil spring deforms with the steel ball being pushed to the engagement teeth, a rotation of the bezel is allowed. And, every time the bezel rotates by a constant angle, since the steel ball enters between the engagement teeth of the click groove due to a force of the coil spring, the click feeling is given each time. Together with this, by the fact that, in a rotation position at a time point in which a rotation force of the bezel is vanished, the steel ball enters between the engagement teeth of the click groove, the bezel can be retained to a desired rotation position (e.g., refer to JP-A-2003-270365 Gazette (paragraphs 0002-0009, FIG. 3)).
Further, in the leaf spring type, in the back face of the bezel, there is provided the click groove comprising plural irregularities juxtaposed in the rotation direction of this bezel, a leaf spring facing on the click groove is mounted to the case band, and an elastic part cut and stood from this leaf spring is engaged with the click groove. A sectional shape of the click groove forms a shape having a stopper face in a direction perpendicular to the rotation direction of the bezel, in other words, a rectangular shape or a right triangle shape. By this, in a case where the bezel is rotated in one direction previously determined, it is possible to give the click feeling every time the bezel rotates by the constant angle with the elastic part being removed from the click groove. Further, in a case where the bezel is rotated in a direction reversed to the former direction, there is made such that a tip of the elastic part is caught to the stopper face and engaged with the click groove such that the bezel does not rotate reversely (e.g., refer to JP-UM-A-5-92779 Gazette (paragraphs 0007-0010, FIG. 1-FIG. 3)).
In the conventional example of the above click ball type, although the bezel can be rotated in any direction of the clockwise direction and the counterclockwise direction, since a retention of the bezel to the desired rotation position depends only on a force of the coil spring, a reliability for retaining the bezel to the desired rotation position is low. Therefore, there is the fact that the bezel is carelessly rotated by an external force acting on the bezel at a carrying time of the timepiece.
Further, in the conventional example of the leaf spring type, since the rotation of the bezel is regulated to only one direction, in a case where the bezel is rotation-operated while slightly deviating from the desired rotation position due to a wrong operation, it is impossible to reversely rotate the bezel. Therefore, the bezel must be aligned with the desired rotation position by being rotated again by approximately one rotation, so that time and effort are required. Not only it, in a case where, at a carrying time of the timepiece, an external force acts in a direction along which the rotation of the bezel is allowed, there is also a fear that the bezel is carelessly rotated.